Stable colloidal solution of iodine



Patented Dec. 3, 1935 UNITED STATES STABLE COLLOIDAL SOLUTION F IODINEWilliam M. Malisoii, Philadelphia, Pa., assignor,

by mesne assignments, to Mackie-Henkels, Inc., Philadelphia, Pa., acorporation of Pennsylvania No Drawing. Application July 19, 1933,Serial No. 681,163

8 Claims. (01. 252-6) In the employment of iodine as an antiseptic orfor any particular medical purpose the use of an aqueous colloidalsolution or dispersion associated with colloidal solution is highlydesirable.

Such solutions may be expected to be non-irritating, more active and atthe same time less toxic than alcoholic tinctures, and the like. At thesame time it is a prime requisite that such solutions remain stableduring the period follow- 10 ing manufacture and preceding actualmedical use. In iodometry dispersions of iodine or starch serve asindication of the progress of certain reactions, and it is possible thatthe idea of using such dispersions medically may have occurred to someone. Nevertheless, these dispersions are not stable and are not useful.The color fades, precipitation occurs, or side-reactions occur,.according to conditions. On the other hand definite medical use hasbeen made of the insoluble, undispersed reaction product of starch withiodine in high concentration, a brownish powder which shows slightdispersion only when wetted.

I have discovered a method and'means of preparing a stable, colloidaldispersion of iodine in water which will not precipitate nor willrequire being put up in insoluble solid or semi-solid form, as thetraditional starch-iodine complex. For this purpose I submit starch,which may originate from any vegetable source, to a preliminary 3fractionation designed to separate undesirable ingredients, to wit, agroup of amylopectins and substances other than the amyloses. Theamyloses are preferably further fractionated into the alpha and betaforms. The former is used as the colloid dispersing and adsorbing mediumfor dispersing the iodine in water.

I do not wish to restrict myself to any particular method of separation,since the spirit of my invention is to embody the discovery that alphaamylose no matter how obtained will form a stable dispersion withiodine, hitherto not conceived of or employed for medical purposes,possessing the distinct advantage of constancy of composition throughlong periods of time, uniformity, standardizability for pharmacopoeiaspecifications, and smoothness and reliability in use clinically.

As an example only I will indicate that the pectinic impurities may beseparated by boiling up starch in water and filtering through clay,kaolin, bentonite, paper pulp, filter-cell, silica gel, or similarmaterials. The amyloses may be separated by electrophoresis at selectiverates, for instance continuously in a 3-compartmfent electrolytic cell.Thus one obtains substantial but not complete freedom from phosphoruscompounds as well. Conditions are set for obtaining the fraction ofhighest specific optical rotation (about and lack of precipitation withalcohol in the absence of electrolytes. I prefer to use this fraction toform a dispersion of 0.5-2% by weight of alpha amylose. This is readilyaccomplished by heating. This solution 5 will disperse free iodine onagitation directly from the solid or from a solution of the same iniodides. The presence of a small amount of iodides and/or of chloridesmay be of use, should one wish to form an isotonic solution containing10 some sodium chloride or the like. The stability remains unaffected.For most therapeutic purposes it is suificient to introduce 0.1 to 0.2%of iodine only, forty percent of which may be in the form of iodideswhich up to this concentra- 15 tion do not depress the stability.

What I claim is:

1. A method for producing a stable colloidal dispersion of iodineconsisting of agitating free iodine with a dispersion of alpha amyloseand 20 starch residues substantially free of beta amylose.

2. A method for producing a stable coloidal dispersion of iodineconsisting of agitating free solid iodine with a dispersion of alphaamylose 25 and starch residues substantially free of beta amylose.

3. A method for producing a stable colloidal dispersion of iodineconsisting of agitating free iodine in a solution of iodides with adispersion of 30- alpha amylose and starch residues substantially freeof beta amylose.

4. A composition of matter comprising a stable colloidal dispersion ofiodine in water by the agitation with free iodine of alpha amylose and 3starch residues substantially free of beta amylose.

5. A method for producing a stable colloidal dispersion of iodineconsisting of agitating free iodine with a dispersion of substantially.5% to 2% by weight of alpha acylose and starch resi- 40 duessubstantially free of beta amylose.

6. A composition of matter comprising a stable colloidal dispersion ofiodine in water by the agitation of a dispersion of substantially .5%to. 2% by weight of alpha amylose and starch resi- 45 dues substantiallyfree of beta amylose with free iodine of substantially .1% to .2%concentration.

